Keira Knightley has kissed some of the biggest heartthrobs in Hollywood, but her current leading man gets top billing.

“James [McAvoy] is the best kisser ever!” a giggling Knightley, 22, said of her Atonement costar while sitting in romantic Venice.

Despite kissing Johnny Depp and Orlando Bloom, Knightley – who is currently dating actor Rupert Friend – glanced at McAvoy and diplomatically dubbed him the best on the opening day of the Venice Film Festival.

McAvoy, 28, reciprocated the compliment saying, “I was blown away by Keira. The amount of poise and grace she has is just incredible.”

In Atonement, a war drama set in 1935, Knightley plays plays Cecilia Tallis, an upper-class beauty whose fledgling love affair with the housekeeper’s son (James McAvoy) is destroyed by a tragic misunderstanding.

McAvoy – who is married to British actress Anne-Marie Duff – told PEOPLE he was enjoying Venice “very much,” adding, with a smile, “it’s very romantic.”

KEIRA KNIGHTLEY has vowed never to let her guard down and be caught going commando.

The Atonement star - who looked worryingly like ET at the film’s premiere at the Venice Film Festival on Wednesday - said: “I’m not going to get blind drunk and then stumble out and fall over and puke up in front of people.

“I’m not saying I don’t do that in private, but I try not to.”

Sounds to me like you get right on it when out of public view, Keira.

The beauty said she had struggled to maintain her dignity under the glare of paparazzi interest.

And she had a pop at celebs caught flashing their undercarriages.

She told film bible Empire: “The whole celebrity thing is not magic. They’re real people proving they’re s******r than everybody else because they don’t even wear knickers.”

Keira reckons her role as Cecilia Tallis in Atonement, one corner of the strange love triangle at the dark heart of Ian McEwan’s famed novel, is her best and most challenging yet.

She said: “Atonement, it was the first time that I’ve come into a part with any f***ing confidence whatsoever.

“She is nothing like I’ve played before ? she is brittle and she is difficult and she is a complete bitch at the beginning.

“She is like a pressure cooker. It’s like that feeling you get in the summer when there needs to be a thunderstorm.

“I just responded to her.

“It’s a beautiful film. Everybody cared, it was the most rewarding thing.”

Atonement is directed by Joe Wright, who previously guided Keira to a career high as Elizabeth Bennet in Pride & Prejudice.

She added: “I feel like I have really good relationships with two directors and that’s Joe and John Mayberry. And it sounds really f***ing ridiculous, but they were the first two people that actually believed in me.”

The foul language and champagne requests showed a side to the normally demure actress I never knew existed.

Good girl!

Keira Knightley routinely makes World’s Most Beautiful lists – including PEOPLE’s, in 2005 – but the actress is somewhat bewildered by the widespread interest in her looks.

“Somebody goes, ‘Gosh, you’re pretty,’ ” Knightley, 22, tells the U.K.’s Radio Times. “Thanks. I’ve got good genes!

But she can’t just credit her family, she admits, saying: “OK, I’m on the cover of a magazine but somebody else does the hair, and the makeup, and airbrushes the f— out of me – it’s not me, it’s something other people have created.”

The Pirates of the Caribbean star – who replaced Kate Moss as the face of Chanel’s Coco Mademoiselle fragrance – says she also can’t understand people’s obsession with wanting to be well-known.

“It frightens me when kids go, ‘I want to be famous,’ ” she says. “Why? Because you can get into a restaurant? You know what? If you book [a table], you can get into a restaurant! ‘I want to be rich and famous.’ Go and work on the stock market.”

Knightley’s fear about the reaction of “kids” was dealt with in January, when she successfully sued Britain’s Daily Mail for suggesting she had an eating disorder.

“You couldn’t say anything more horrendous,” Knightley said of the newspaper’s claims about her thin looks – which, she explained at the time, had to do with the arduous work on the final Pirates movie. “So yes, I did take a hard line, and I would take that line again.”

Knightley is comfortable with herself now, but says in her teens she was too self-conscious to even watch her own rushes, because, she says, “When I was 16, 17, I felt incredibly awkward about the way I looked.”

FILM beauty

KEIRA KNIGHTLEY has hit out at young people who crave fame and fortune.

She said: “It frightens me when kids go, ?I want to be famous’.

“Why? Because you can get into a restaurant? You know what? If you book, you can get into a restaurant!’”

The Pirates Of The Caribbean star, 22, also complained about the world’s obsession with her looks.

She told the Radio Times: “OK, I’m on the cover of a magazine but somebody else does the hair, and the make-up, and airbrushes the f*** out of me ? it’s not me, it’s something other people have created.“

Keira also revealed that she sided with critics who said her acting in 2002 breakthrough movie Bend It Like Beckham was “rubbish”.

The star, whose new film Atonement is released next month, said: “I completely agreed on every level.”